The researchers found that weather and climate are significant factors
affecting soybean seed tocopherol content. Tocopherols are a family of
antioxidants that protect biological membranes. Among this family,
alpha-tocopherol is the active form of vitamin E in humans.

Soybean seeds are a major source of vegetable oil in the U.S. diet,
and consequently a major contributor to dietary tocopherol intake. The daily
Recommended Dietary Allowance for vitamin E for men and women aged 14 and older
is 15 milligrams. But more than 50 percent of American adults do not get
adequate amounts of vitamin E, according to experts.

For the study, the researchers analyzed the content of tocopherols in
soybean seeds grown at several locations in Maryland between 1999 and 2002.
Weather was relatively normal between 1999 and 2001, but extreme drought and
warmer temperatures characterized 2002.

Since soybeans mature at different rates, the researchers examined up
to 18 soybean lines representing different maturity groups. There were small
but significant increases in the proportion of alpha-tocopherol in beans from
the same genetic line grown in warmer, full-season Eastern Shore locations
compared to beans that matured under slightly cooler conditions.

But under extreme drought conditions in 2002, early maturing lines had
as much as a 3.5-fold increase in relative alpha-tocopherol content, compared
to the other years during which rainfall was adequate.

The field studies showed how nutritional properties of crops can be
dramatically affected by weather and potentially by global environmental
change, according to the authors.